This invention relates to air coolers and, in particular, to low profile unit coolers utilizing refrigeration cooling.
Low profile unit coolers are designed to cool a variety of spaces such as walk-in coolers, beverage boxes, meat cutting and storage rooms, and produce storage areas. The coolers have been widely used due to their high output and compact size. Typically, the coolers are supported in the upper part of a room and have a short side profile so that floor space is not sacrificed.
The coolers incorporate an elongate, continuous coil which is secured at either end by a support member. The support member typically includes a vertical plate containing pairs of holes through which the tubes of the coil extend. The coils are formed by inserting the open ends of U-shaped tubes through the pairs of holes in the vertical plates and by connecting these open ends to one another with short U-shaped lengths of tubing.
A number of thin rectangular heat exchange fins containing holes which correspond to those of the end support members are generally fitted over the lengths of tubing before the tubes are connected. The fins are equally spaced along the tubes in order to facilitate the exchange of heat between the coils and the surrounding air. Although the spacing of the fins varies depending on the expected use of the cooler, the fins typically are spaced between 1/4" and 1/8" apart.
The units are enclosed by elongate, box-shaped, rustproof outer housings and include one or more electrical fans which circulate the cooled air.
When a unit is operating, condensation has a tendency to form on the heat exchange fins and the refrigeration coil. If ice forms on the coil and fins, defroster heat is provided periodically, causing the frozen condensate to melt. A drainage pan secured to the base of the cooler housing catches this condensate as it drips from the fins and the coil. To prevent the condensate from freezing and plugging the pan's drain, the coolers are provided with either electric or gas drainage pan defrosters.
The electric defrosters are usually simple U-shaped resistance heaters which are connected by wires to the electrical circuit box of the cooler unit. These resistance heaters are typically secured to the drainage pan by means of brackets. Unfortunately, the use of brackets adds to the overall cost of the unit both in terms of materials and labor. The materials costs increase due to the cost of the brackets themselves and the labor costs increase due to the time required to secure the brackets to the drainage pan.
The brackets also pose a potential sanitation problem. One possibility is that the brackets themselves will contaminate the unit. Additionally, because the brackets have a tendency to trap sediment and make it difficult to properly clean the drainage pan, the brackets may accentuate the possibility of contamination due to other causes.
The use of brackets also leads to other maintenance problems. Specifically, the most convenient means of repairing or maintaining the internal components of the cooler is to remove the drainage pan. Unfortunately, the drainage pan can not be completely removed from the cooler because the electrical connections between the control box and the resistance heater are too short. As a result, maintenance and repair work on the internal components of the cooler is less convenient and more time consuming.
One method of avoiding some of the drawbacks inherent in bracketing a resistance heater to a cooler's drainage pan is to suspend the resistance heater from the refrigerator coil by wires. This involves the relatively difficult task of wrapping one end of the wires between the narrowly spaced heat exchange fins and around the tubes of the refrigeration coil, and wrapping the other end of the wires around the resistance heater. This procedure has proved unsatisfactory due to the time and effort required to perform it.
Cooler units can also be provided with gas heat defrosters, rather than electric defrosters. The gas defrosters are typically U-shaped tubes containing hot gas. Commonly, brackets are used to suspend the gas filled tubes from the cooler's end support units.
As with the case of the electrical defroster, the use of brackets to secure the defroster adds to the overall cost of the cooler both in terms of materials and labor.
Thus, there is a need for a new and improved cooler in which cooler drainage pan defrosters can be more easily and efficiently secured.